As UN delegates vote on Australia's bid for a Security Council seat, questions remain about the cost and value of the campaign and the methods used to pursue it.

Australia is competing against Finland and Luxembourg for two places on the council, with voting beginning early Friday morning (AEDT) in New York.

The Security Council is made up of five permanent members and 10 non-permanent members.

Among the competition, Finland is seen as the strongest rival, Luxembourg the long shot. The ballot is secret, so estimating the level of support is difficult and some ambassadors play games.

Australia needs 129 votes to win one of the two spots on offer, and last night Foreign Minister Bob Carr said the vote was too close to call.

"Well it's been – there have been wins and losses," he said.

"We've had nations tell us candidly they're not supporting us.

"Others have confirmed their support and that confirms we've got substantial cross-regional support, but the diplomats working for Australia here tell me the best judgment is that it's going to be close."

The bid for a seat has run for four years and cost tens of millions of dollars.

The exercise was a personal obsession of Kevin Rudd – as prime minister, he made it his mission to promote the bid all over the world.

The man who began the lobbying effort, former Australian ambassador to the United Nations Robert Hill, says it is an important position to strive for.

"It's worth it if you believe, as I do, that Australia should be making a contribution to a more peaceful and stable world," he told 7.30.

"In some cases bids will have been - votes will have been bought, I should say, two or three times, maybe more and the highest bidder can still ultimately be betrayed," he said.

"So it's very hard to know exactly what will happen until the night.

"I think the motivations are quite clear. Although the Government is often reluctant to admit it at the risk of being seen as insincere, the motivations are to coddle favour and to essentially buy votes for our UN Security Council bid."

Since the bid began, aid for Africa, home to 53 votes, has trebled.

Funding for the Caribbean, home to 15 votes, has gone from zero to almost $50 million this year.

Some of those who spend the money, like charity Action Aid, say there is no doubting the link.

Many of its projects are in Sub-Saharan Africa, helping the poor feed themselves, form part of a new funding program established since the UN bid began.

Action Aid executive Archie Law used to work for the UN Development Program, and says Africa has seen more aid since the bid got underway.

"There's little doubt that the UN Security Council bid has led to an increase focused on aid in Africa," he said.

"You just need to go to the Department of Foreign Affairs' website and it's all over it.

"And for us at Action Aid, that's a great thing to happen."

But political analyst Thom Woodroofe, who has studied the process since it began, says it is difficult to draw a conclusion that the aid boosts are aimed at securing the seat.

"What a lot of people that make this suggestion perhaps forget, is that the decision to double the aid budget in 2007 over a long period of time predated the campaign. And Australia is going through the growing pains of expanding that aid at the moment," he said.

"So I think it's a little bit unfair to say a lot of Australian aid has been redirected. Certainly we've started providing aid perhaps in greater quantities or to new places, but certainly not just wholly at the expense of the Security Council vote."